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From "Maxim Novikov (JIRA)" <>
Subject [jira] [Updated] (SOLR-5821) Search inconsistency on SolrCloud replicas
Date Sat, 05 Apr 2014 09:38:15 GMT


Maxim Novikov updated SOLR-5821:

    Attachment: Screen Shot 2014-04-05 at 2.26.41 AM.png
                Screen Shot 2014-04-05 at 2.26.26 AM.png

SolrCloud infrastructure:

3 ZooKeeper nodes + 3 Solr replicas (1 shard) on Tomcat 7.

When importing the data from the database through one of the Solr instances (DataImportHandler)
another Solr instance was down (had to be restarted). The result of that you can see in the
screenshots. The number of items on 1st machine is 9,812,001 items, on that one that was down
for a couple of seconds is 9,811,987.

PS And the worst thing is that I can't see a way to synchronize them now, as replication requests
via HTTP don't seem to be working as in SolrCloud all the nodes behave like "masters" and
HTTP replication request (pulling data from the master to a slave) just fails. But even if
it worked, it wouldn't be really appropriate. That way you would need to perform consistent
checks all the time (as data continues coming), and do something on your own...

> Search inconsistency on SolrCloud replicas
> ------------------------------------------
>                 Key: SOLR-5821
>                 URL:
>             Project: Solr
>          Issue Type: Bug
>          Components: SolrCloud
>    Affects Versions: 4.6.1, 4.7.1
>         Environment: SolrCloud:
> 1 shard, 2 replicas
> Both instances/replicas have identical hardware/software:
> CPU(s): 4
> RAM: 8Gb
> HDD: 100Gb
> OS: CentOS 6.5
> ZooKeeper 3.4.5
> Tomcat 8.0.3
> Solr 4.6.1
> Servers are utilized to run Solr only.
>            Reporter: Maxim Novikov
>            Priority: Critical
>              Labels: cloud, inconsistency, replica, search
>         Attachments: Screen Shot 2014-04-05 at 2.26.26 AM.png, Screen Shot 2014-04-05
at 2.26.41 AM.png
> We use the following infrastructure:
> SolrCloud with 1 shard and 2 replicas. The index is built using DataImportHandler (importing
data from the database). The number of items in the index can vary from 100 to 100,000,000.
> After indexing part of the data (not necessarily all the data, it is enough to have a
small number of items in the search index), we can observe that Solr instances (replicas)
return different results for the same search queries. I believe it happens because some of
the results have the same scores, and Solr instances return those in a random order.
> PS This is a critical issue for us as we use a load balancer to scale Solr through replicas,
and as a result of this issue, we retrieve various results for the same queries all the time.
They are not necessarily completely different, but even a couple of items that differ is a
deal breaker.
> The expected behaviour would be to always get identical results for the same search queries
from all replicas. Otherwise, this "cloud" thing works just unreliably.

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